The present invention relates to a shadow mask assembly of a color cathode ray tube and, more particularly, to an improvement in a structure for supporting a shadow mask inside a skirt of a panel.
In a conventional shadow mask type color cathode ray tube, shadow mask 26 having a plurality of small slit-like apertures 21 and being made of a thin metal plate, as shown in FIG. 1, is welded and fixed on rectangular frame 27. Shadow mask assembly 20 has resilient deformable support 28 welded and fixed at substantially a central portion of each side of frame 27, and is arranged in a glass panel (not shown). A hole formed at a distal end of each support 28 is fitted with a stud pin (not shown) fixed at an inner surface of the glass panel so as to suspend and hold assembly 20 at a predetermined position inside the panel. In assembly 20, outer surfaces of corners of frame 27 are curved for the sake of easy making.
In a system recently proposed, a resilient support is fixed not at the central portion of each side of a rectangular frame but at each corner, a stud pin is provided on the inner surface of the glass panel to correspond to each corner, and the support is engaged with the stud pin, thereby holding the shadow mask within the panel.
When a resilient deformable support is fixed at a corner of a rectangular frame and the outer surface of the corner is curved, part of the support must be curved to substantially correspond to the corner of the frame so that the support can be brought into tight contact therewith and be firmly fixed thereon. However, it is difficult to work a resilient deformable support of such a shape. In addition, since the support is curved, its elasticity becomes excessive, i.e., its spring back force becomes too large. As a result, loading/unloading of the shadow mask, which is repeated several times during manufacture of a color cathode ray tube, becomes difficult. In order to prevent this, the resilient deformable support is made to have a complex shape, or an auxiliary member is needed in addition to the frame and the support, as shown in Japanese Pat. Disclosure No. 57-187839. This leads to an increase in manufacturing costs as well as displacement of the shadow mask caused upon repeated loading/unloading thereof. Such displacement of the shadow mask should be avoided in a color cathode ray tube.